Although the Dow Jones Industrial Average is tumbling 719 points, in danger of the biggest price decline since March 22, and the S&P 500 is shedding 2.8%, the NYSE's Arms Index suggests sellers are still relatively calm and that panic-like selling hasn't taken hold--yet. The Arms Index is a volume-weighted breadth tracker. It tends to rise above 1.000 when the market falls, as the ratio of volume in declining stocks over advancing stocks usually increases relative to the ratio of declining stocks to advancing stocks. Arms readings above 2.000 suggest panic-like selling. Currently, the NYSE Arms is at 1.638, while the reading for Nasdaq is 1.038. Separately, the so-called fear index, or CBOE Volatility Index , which measures bearish and bullish options bets on the S&P 500 in the coming 30 days, was hanging around 20, near its historical average, when much higher levels would ordinarily be in effect. A day ago, the stock market climbed with risk appetite as President Donald Trump and China's leader Xi Jinping forged a momentary pause in trade hostilities at the sidelines of the Group of 20 summit in Argentina. However, investors have grown doubtful that a real deal in the long-run is possible. On top of that, the 10-year Treasury rate has extended a drop toward a three-month low at 2.90%, with that move also narrowing a closely watched spread between that benchmark government debt and the short-dated 2-year Treasury note . That spread is the tightest since 2007 at 10 basis points, with a tightening, or flattening, spread between the short-dated and longer-dated bonds, generally reflecting that bond investors harbor a downbeat economic outlook.